Breech assembly for an electrothermal gun

ABSTRACT

This invention relates to a breech assembly of a gun adapted to fire caseless charges, ignited and enhanced with electrothermal chemical (ETC) charges. The gun utilizes charges as propellant and a plasma generator cartridge (PGC) for generating plasma when an electrical current is applied thereto. The breech assembly comprises a breech ring, a tilting block assembly, with a spindle installed and a sliding block for supporting or locking the tilting block assembly in a sealed position. The tilting block assembly is movable between a PGC firing orientation and a PGC loading/removal orientation. The breech assembly further includes a crank means, which includes a guide means for rotating the tilting block assembly from the PGC firing orientation to the PGC loading/removal orientation.

This application is the US national phase of international applicationPCT/ZA03/00027, filed 20 Feb. 2003, which designated the US and claimspriority to ZA Application No. 2002/1546 filed 25 Feb. 2002. The entirecontents of these applications are incorporated herein by reference.

INTRODUCTION AND BACKGROUND TO THE INVENTION

This invention relates to a breech assembly for an electrothermal gun, agun provided with such a breech assembly and an obturation assembly fora gun.

A conventional tilting block assembly for a gun such as a cannon or thelike, comprises a spindle having a shaft and a mushroom shaped head; andan obturation set including a resilient obturator pad for mating withand sealing against an obturation seat, an inner ring and two retainingrings. The obturation seat is usually defined by the rim of the mouth ofa barrel at the rear end of the firing chamber. When the spindle isdisplaced axially relative to the barrel by the combustion of apropellant charge in the firing chamber, the obturator pad deformsradially outwardly into sealing engagement with the obturation seat,with the retaining rings limiting deformation of the obturator pad andpreventing extrusion of the obturator pad.

The tilting block assembly is usually held in position by a crank armand rollers, which are supported by the breech ring of the gun and theshaft of the spindle usually extends through a hole in the tilting blockassembly abutting a sliding block. Although this application is for theloading and firing of a front loaded plasma generator cartridge (PGC),it is also possible to machine a chamber in the rear end of the spindlefor a cased primer for igniting the propellant charge, and a so calledprimer head space is defined between the rear end of a primer case andthe front face of the sliding block.

It is known to use a plasma generator cartridge (PGC) to generate plasmawhen high-voltage is applied thereto. Various examples of PGC's and/orelectrothermal chemical (ETC) applications are disclosed in thefollowing U.S. Pat. Nos. 4,640,180 4,895,062 5,042,359 5,171,9325,183,956 5,612,506 5,675,115 5,898,124 5,945,623 5,988,070.

A common disadvantage of all the above arrangements is that the PGC isloaded from the rear into a carrier mechanism, such as a stub case orspindle arrangement, causing sealing problems between the PGC and thecarrier mechanism. Another disadvantage is that the rear inserted PGCincreases the time required for loading the PGC and charge duringsustained and rapid fire. The use of cases for the main obturation andPGC carrier, further increases the overall operational cost per firedshot. Further disadvantages of the known systems are that the PGC's andstub cases are strewn around the inside the turret of the gun and thatthe sealing efficiencies of the known obturation assemblies are notreliable.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a breech assemblyfor an electrothermal gun, a gun provided with such a breech assemblyand an obturation assembly for a gun with which the aforesaiddisadvantages can be overcome or at least minimised.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a guncomprising a breech assembly adapted to receive a caseless charge and aplasma generator cartridge (PGC).

According to a second aspect of the invention there is provided a breechassembly adapted to fire a caseless charge with the aid of a plasmagenerator cartridge (PGC), the breech assembly comprising a tiltingblock assembly having a sealing side and an opposite rear side, thesealing side being adapted to receive an obturation set and a spindlehead which is adapted to receive a PGC for generating plasma.

Further according to the invention, the tilting block assembly may bemovable between a sealed position and an open position.

The breech assembly may further include a sliding block and a breechring for retaining the tilting block assembly in the sealed and openpositions.

The tilting block assembly may further be movable between a PGC firingorientation and a PGC loading/removal orientation.

The tilting block assembly spindle head may be adapted to receive thePGC from the side of the sealing face when in the open position and thePGC loading/removal orientation.

The breech assembly may further include a crank means for rotating thetilting block assembly from the PGC firing orientation to the PGCloading/removal orientation when the tilting block moves from the sealedposition to the open position.

The tilting block assembly may be pivotally mounted on the crank means,relative to the breech assembly, for rotation about a first axis ofrotation, from the sealed position to the open position.

The crank means may further include a guide means for guiding rotationof the tilting block assembly form the PGC firing orientation to the PGCloading/removal orientation, when the tilting block assembly moves fromthe sealed position to the open position.

The tilting block assembly may further be pivotally mounted on the crankmeans for rotation about a second axis between the PGC firingorientation and the PGC loading/removal orientation.

The crank means may include a crank arm of which a first end may bepivotally connected to the breech ring by a spline shaft and a secondend of which may be pivotally connected to the tilting block assembly bya stub shaft.

The guide means may be in the form of a tilting block assembly firstroller running in a first guide slot. Preferably the tilting blockassembly first roller is disposed on the tilting block assembly and thefirst guide slot defined by the breech ring.

A tilting block assembly second roller may run in a second elongatedguide slot. The second slot may be defined by the breech ring.

The stub shaft may further vary in position in a slot in the crank arm.

The sliding block may be slidably movable between a closed positionwherein the tilting block assembly is retained in the firing orientationand a displaced position wherein the tilting block assembly is free topivot to a loading/removal orientation.

According to a third aspect of the invention there is provided anobturation assembly for a gun of the type comprising a barrel of which arear end defines a firing chamber having an obturation seat and the gunfurther having a breech ring; and a tilting block assembly which ismovable between a sealed position and an open position, the obturationassembly comprising:

-   -   an obturation set including an annular obturator pad for sealing        against the obturation seat when in the sealed position;    -   an obturation spindle having a shaft and a head, the shaft        extending coaxially through the obturator pad; and    -   PGC receiving means provided in the head.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described further by way of example only withreference to the accompanying drawings wherein:

FIG. 1 is a perspective view of a breech assembly according to apreferred embodiment of the invention, with a tilting block assembly ina sealed position;

FIG. 2 is the same view as that of FIG. 1 with the tilting blockassembly in an open position;

FIG. 3 is a front end view of FIG. 1;

FIG. 4 is a front end view of FIG. 2;

FIG. 5 is a cross-sectional side view along line A-A¹ in FIG. 3;

FIG. 6 is diagrammatical side view of FIG. 1;

FIG. 7 is a diagrammatical side view of FIG. 2; and

FIG. 8 is a diagrammatical cross-sectional side view similar to FIG. 5with some parts removed.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Referring to the drawings, a breech assembly of a gun (not shown)adapted to fire caseless charges, ignited and enhanced withelectrothermal chemical (ETC) charges, is generally designated byreference numeral 10.

The gun utilises charges as propellant and a plasma generator cartridge(PGC) 17 for generating plasma when an electrical current is appliedthereto.

Referring to FIG. 5, the breech assembly 10 comprises a breech ring 13,a tilting block assembly 14, with a spindle 15 installed, having asealing side 14.1 and an opposite rear side 14.2. The sealing side 14.1is the mating side for an obturation set 12 and the spindle 15, of whicha head of the spindle is adapted to load the PGC 17. The tilting blockassembly 14 is movable between a sealed position shown in FIGS. 1, 3, 5and 6, and an open position shown in FIGS. 2, 4, and 7.

The breech assembly 10 further includes a sliding block 16 forsupporting or locking the tilting block assembly 14 in the sealedposition.

The tilting block assembly 14 is further movable between a PGC firingorientation shown in FIGS. 1, 3, 5 and 6, and a PGC loading/removalorientation shown in FIGS. 2, 4, and 7. The spindle head is adapted toload the PGC 17 when in the loading/removal orientation.

The breech assembly 10 further includes a crank means for rotating thetilting block assembly 14 from the PGC firing orientation to the PGCloading/removal orientation when moving from the sealed position to theopen position.

The crank means includes a crank arm 20 of which a first end 20.1 ispivotally connected to the breech ring 13 by a spline shaft 22 and asecond end 20.2, which is pivotally connected to the tilting blockassembly 14 by a stub shaft 24. The stub shaft 24 varies in position ina slot 25 in the crank arm 20.

Referring particularly to FIG. 8, the crank means further includes aguide means generally designated by reference numeral 26 for guidingrotation of the tilting block assembly 14 form the PGC firingorientation to the PGC loading/removal orientation, when the tiltingblock assembly 14 moves between the sealed and the open positions.

The guide means 26 is in the form a tilting block assembly second roller26.1 disposed on the tilting block assembly 14 and running in a secondguide slot 26.2 defined by the breech ring 13.

The guide means 26 is further in the form of a tilting block assemblyfirst roller 26.4 disposed on the tilting block assembly 14, for runningin an elongated L-shaped first guide slot 26.3 defined by the breechring 13.

The sliding block 16 is slidably movable between a closed positionwherein the tilting block assembly 14 is retained in the firingposition, and a displaced position wherein the tilting block assembly 14is free to pivot to the open position.

The tilting block assembly 14 houses a spindle 15, defining a spindlehead. The head is disposed on the sealing side 14.1 of the tilting blockassembly and defines a PGC loading formation in which the PGC 17 isdisposed.

In use, the sliding block 16 is moved from the closed position to thedisplaced position. The crank arm 20 is pivotally movable as indicatedby arrow A in FIG. 8, about the spline shaft 22, to move the tiltingblock assembly 14 from the sealed position to the open position. Whileso moving, the tilting block assembly 14 is pivoted by the guide means26 from the PGC firing orientation to the PGC loading/removalorientation, in that the tilting block assembly second roller 26.1 andtilting block assembly first roller 26.4 follow the slots 26.2 and 26.3respectively.

In the PGC loading orientation, a PGC 17 is located in the PGC loadingformation. A charge (not shown) is loaded into the barrel chamber of thegun. Subsequently, the procedure is reversed by pivoting the crank arm20 about the spline shaft 22 to move the tilting block assembly 14 tothe sealed position. In the process, the tilting block assembly ispivoted from the loading orientation to the firing orientation, by theguide means 26. The sliding block 16 is moved to the closed position.The gun is now ready to be fired. When the tilting block assembly 14 ismoved back to the PGC removal orientation after the gun has been fired,the fired PGC 17 is obviously removed first before the next one isloaded in the PGC loading formation.

The applicant has found that the breech assembly 10 according to theinvention is highly efficient and saves operational time and costs. Theapplicant has further found that superior obturation is obtained with atilting block assembly 14 and an obturation assembly, according to theinvention in that there is a positively sealed passage defined betweenthe front and rear ends of the spindle, containing the loaded PGC 17.

It will be appreciated that variations in detail are possible with abreech assembly for an electrothermal gun, a gun provided with such abreech assembly and an obturation assembly for a gun without departingfrom the scope of the appended claims.

1. A gun comprising a breech assembly adapted to receive a caselesscharge and a plasma generator cartridge (PGC), and to fire the caselesscharge with the aid of the PGC, the breech assembly comprising: atilting block assembly movable between a sealed position and an openposition, and having a sealing side and an opposite rear side, thesealing side being adapted to receive an obturation set and a spindlehead which is adapted to receive a PGC for generating plasma, a slidingblock and a breech ring for retaining the tilting block assembly in thesealed and open positions, the tilting block assembly being furthermovable between a PGC firing orientation and a PGC loading/removalorientation, and a crank means for rotating the tilting block assemblyfrom the PGC firing orientation to the PGC loading/removal orientationwhen the tilting block moves from the sealed position to the openposition, wherein the tilting block assembly is pivotally mounted on thecrank means, relative to the breech assembly, for rotation about a firstaxis of rotation, from the sealed position to the open position, andwherein the crank means is pivotally mounted on the breech ring.
 2. Thebreech assembly according to claim 1 wherein the sliding block isslidably movable between a closed position wherein the tilting blockassembly is retained in the firing orientation and a displaced positionwherein the tilting block assembly is free to pivot to a loading/removalorientation.
 3. The breech assembly according to claim 2 wherein thetilting block assembly spindle head is adapted to receive the PGC fromthe side of the sealing face when in the open position and the PGCloading/removal orientation.
 4. The breech assembly according to claim 1wherein the crank means includes a guide means for guiding rotation ofthe tilting block assembly from the PGC firing orientation to the PGCloading/removal orientation, when the tilting block assembly moves fromthe sealed position to the open position.
 5. The breech assemblyaccording to claim 4 wherein the tilting block assembly is pivotallymounted on the crank means for rotation about a second axis between thePGC firing orientation and the PGC loading/removal orientation.
 6. Thebreech assembly according to claim 5 wherein the guide means is in theform of a tilting block assembly first roller running in a first guideslot.
 7. The breech assembly according to claim 6 wherein the tiltingblock assembly first roller is disposed on the tilting block assemblyand the first guide slot is defined by the breech ring.
 8. The breechassembly according to claim 7 wherein a tilting block assembly secondroller runs in a second elongated guide slot.
 9. The breech assemblyaccording to claim 8 wherein the second guide slot is defined by thebreech ring.
 10. The breech assembly according to claim 1 wherein thecrank means includes a crank arm of which a first end is pivotallyconnected to the breech ring by a spline shaft and a second end of whichis pivotally connected to the tilting block assembly by a stub shaft.11. The breech assembly according to claim 10 wherein the stub shaftvaries in position in a slot in the crank arm.